This invention relates generally to systems and methods of dermal drug and chemical delivery, and more particularly, to a system and methods for local intradermal prophylaxis and treatment of pathogens introduced by dermal injury from a known vector.
Many disease causing agents, including bacteria, viruses, protozoans, toxins and venoms, are introduced by innoculation into or through the skin, for example by dermal injuries such as insect, spider or snake bites, other skin punctures such as needle sticks, or through abrasions. During the initial stage of infection or envenomation, many of these agents remain localized in an area within centimeters of the initial innoculation site, and only later begin to affect the body systemically. A classic example is Lyme borreliosis, commonly known as Lyme disease, produced by a tick-borne spirochete. The typical clinical course of the disease begins with innoculation through the bite of an infected tick, followed by the appearance of the distinctive, xe2x80x9cbulls-eyexe2x80x9d erythema migrans rash at the site of innoculation. It is believed that the spirochete initially remains localized in the skin for a period of days before multiplying to establish infection.
In later stages of infection the spirochetes disseminate and can be found in remote skin sites, blood, cerebrospinal fluid, synovial fluid, and other tissues. Later stage Lyme disease symptoms include joint swelling and arthritis; carditis; memory loss, localized paralysis, paresthesias and other symptoms of CNS involvement; and nonspecific symptoms such as fatigue. Once this stage of infection has been reached, eradication of the spirochete and elimination of Lyme disease symptoms can prove frustratingly difficult. Systemic administration of antibiotic is the standard treatment, but even with aggressive, systemic antibiotic treatment during the early stage of the disease, the treatment failure rate for documented Lyme disease can be as high as 10%. Still, general agreement exists that the earlier and more aggressive the treatment, the better the patient outcome.
However, aggressive treatment at the earliest stage possible, that is immediately after a feeding tick has been spotted and removed, is controversial. Many health care workers question the advisability of oral systemic, prophylactic antibiotic therapy for tick bites, which entails days or weeks of exposure to systemic antibiotics. The cost and side effects associated with so treating the enormous number of tick bites incurred each year must be weighed against the relatively small chance of actual disease transmission of an admittedly serious illness. The treatment controversy is further complicated by the fact that some other tick-vectored illnesses, particularly Rocky Mountain Spotted Fever and Ehrlichiosis, can and do kill otherwise healthy individuals, especially children. A premium therefore exists on finding a way to safely and effectively treat such infections at the earliest possible stage.
Like Lyme borreliosis, many other diseases follow a similar pattern of localized innoculation followed by later systemic infection. These include the other tick-vectored illnesses such as Q-fever, Babesiosis, Tularemia, and relapsing fevers, as well as Rocky Mountain Spotted Fever and Ehrlichiosis. Malarial infection by mosquito vectors follows a similar pattern, as do envenomations from bites of arthropods such as the brown recluse spider. Needlestick injuries also carry the risk of hepatitis-B, syphilis, HIV and other infections following the same pattern of initially localized infection, with devastating later stage systemic effects. As with the treatment of Lyme borreliosis, the chances of treatment success for all of these illnesses are greatly enhanced by catching and treating the infection or envenomation at the site of innoculation before systemic dissemination of the pathogen or toxin. Further, because some of these pathogens are known to remain viable in stored blood for up to about two weeks, early treatment and eradication of pathogens before they invade the circulatory system would improve the safety of the blood supply.
The known treatments for such infections or envenomations after localized innoculation consist of an aggressive course of antibiotic or antiviral medication administered systemically. Depending on the pathogen involved and the timing of the treatment relative to the moment of innoculation, such treatments can have a high success rate. However, high systemic doses of antibiotics or antivirals frequently have side effects such as allergic reactions, severe gastrointestinal disturbance, ototoxicity, renal toxicity, pericarditis, etc. The risk of such side effects is particularly vexing in combination with the need for early and aggressive treatment in order to reduce the risk of treatment failure. Furthermore, at least in the case of the Lyme disease spirochete, aggressive systemic antibiotic treatment does not preclude survival of viable bacteria in sequestration.
Transdermal drug delivery systems are known. With such systems are used to infuse drugs systemically at a stable rate over an extended period of time of hours or days. These infusion systems, typically in the form of patches, are used, for example, to deliver compositions containing a single systemically acting drug such as nicotine, nitroglycerin, estradiol, or scopolamine. However, the use of intradermal, local drug delivery for prophylactic and local treatment of infections resulting from innoculations such as bites or needle-sticks is not known.
It would therefore be desirable to provide systems and methods for local, intradermal prophylaxis and treatment of innoculations. It would also be desirable to provide systems and methods which treat innoculations at the earliest stages of potential infection or envenomation. It would be further desirable to provide such systems and methods which are targeted against specific vectors. It would be still further desirable to provide such systems and methods including both early and later, ongoing treatment of innoculations. It would be yet still further desirable to provide such systems and methods which are simple to use for non-medically trained individuals.
In an exemplary embodiment, a system and methods for local intradermal treatment of pathogens includes a vector-specific pharmaceutical composition including drugs or chemicals, or combinations thereof, specifically targeted against a pathogen or pathogens, including bacteria, viruses, toxins, protozoa and venoms known to be carried or potentially carried by the identified vector. The pharmaceutical composition is applied to an area of skin surrounding the site of a dermal injury inflicted by the known vector, the dermal injury thus carrying the risk of innoculation with a pathogen or pathogens from the identified vector. For example, such dermal injuries include insect, snake and arthropod bites, accidental needlesticks, and abrasions. The pharmaceutical composition includes a drug, multidrug, chemical or multichemical combination, plus an enhancer or enhancers for facilitating the penetration and absorption of the pharmaceutical composition into the dermal layers at the site of dermal injury. More specifically, and in one aspect, the pharmaceutical composition provides local, intradermal drug concentrations which are sufficient to substantially eradicate or inhibit a pathogen while it remains localized.
The local intradermal system and methods provide intradermal prophylaxis and treatment of innoculations during the early, localized stages of infection or envenomation. In addition, the system and methods can provide later, ongoing treatment against any surviving pathogens. Further, the local intradermal system and methods are targeted against specific, readily identifiable vectors and their associated pathogens, and are simple to use for non-medically trained individuals. Still further, the system and methods are compact, lightweight and easily packed in gear such as camping gear, emergency gear and the like.